Often we are asked when we move an existing site into Concrete5 if the site's search engine ranking is going to drop with the change to Concrete5. Our experience has been that in most cases the keyword ranking after the move to concrete5 actually improves slightly. One reason might be the dynamic XML sitemap that is created by Concrete5. Another might be the search engine friendly URLs. Lastly, it might be that the page load time is sometimes faster with Concrete5 than other content management systems.
We work with clients of all sizes doing SEO on their websites. The ability to add title tags and meta tags is built right into Concrete5 with no add-ons, modules or plugins required. We have found no limitations with Concrete5 when it comes to search engine optimization and have had a number of sites that instantley moved up in ranking after making the move to Concrete5.